1. Field of the Invention
The invention relates to a steel band for a hose clamp, the steel band comprising at least one pair of end portions which are provided with at least one closed longitudinal slot for guiding therethrough a clamping screw having a head and are bent to form loops. The legs of each loop, in the vicinity of the free end of one leg, are connected to one another and are provided for receiving one of two clamping members, respectively, which clamping members, at least over a portion of their periphery, are cylindrically shaped. One of the clamping members has a transverse opening without a thread for freely guiding therethrough the threaded shaft of the clamping screw, and the other clamping member has a transverse opening with a thread for engaging the threaded shaft of the clamping screw.
2. Description of the Related Art
In such a band for a hose clamp of the aforementioned kind as disclosed, for example, in any of the German patents DE 198 22 915 C1, DE 37 29 372 C2, DE 37 10 852 C1, DE 198 00 283 C1 or the German published patent application DE 39 26 626 A1, the legs of the loop are connected to one another by spot welding. In order to be able to manufacture such a welding connection in a permanent way, the band 1 for a hose clamp is comprised of stainless steel. Stainless-steel is an expensive material. In spite of this, there is still the risk of corrosion at the welding locations. A pre-galvanized band for a hose clamp which is, for example, coated with an alloy of aluminum and zinc, would be less expensive. However, a band for a hose clamp which is treated in this way cannot be welded.
It is an object of the present invention to provide a band for a hose clamp of the aforementioned kind which, while providing high stability under load of the loops in response to the clamping forces, can be manufactured less expensively and more easily.
In accordance with the present invention, this is achieved in that the connection of the legs of each loop is a positive-locking connection.
With such a configuration of the connection it is no longer necessary to employ welding. Also, it is no longer necessary to use stainless steel for the steel band. Instead, low-grade, inexpensive steel can be used which can be made corrosion-resistant by providing a coating.
The positive-locking connection of the legs of the loop can be realized in a simple way in that one leg of the loop is provided with projections projecting away from the plane of that one leg, wherein the projections project into holes of the other leg of the loop, and in that the one leg having the projections of each loop rests against the radially inner side of the band for a hose clamp in an area of the band forming a substantially circular clamp portion. In this connection, the holes can be produced simultaneously with the band for a hose clamp being cut to size from a longer material band by stamping. The projections can be formed in a simple way out of the band for a hose clamp and can be inserted into the holes. The end portion of the radially inner leg of the loop provided with the projections is then pressed during tightening of the hose clamp against the. inner side of the other leg of the loop. This provides an additional frictional connection between the legs of the loop which increases the stability and strength of the connection of the legs of the loop..
Preferably, it is ensured that one leg of each loop is provided with tabs cut out of the band for a hose clamp and bent out of the plane of that one leg, which tabs project through the holes of the other leg of the loop and are bent onto one side of the other leg of the loop. In this connection, producing the tabs and the holes can be carried out simultaneously with the step of cutting to size the band for a hose clamp from the longer material band by stamping. The connection of the tabs and the holes with a corresponding deformation of the tabs can also be realized in a simple way as known and conventional in the art.
Moreover, it is beneficial when at least one pair of tabs is provided whose tabs are bent in opposite directions relative to one another in a direction away from the longitudinal center axis of the band for a hose clamp to the longitudinal edges of the band for a hose clamp. In this configuration the tabs are then loaded as a result of resting against the edges of the holes only by transverse forces and not by bending stress. The positive-locking connection in this way can withstand even higher loads.
Preferably, it is ensured that the holes are wider transverse to the longitudinal direction of the band for a hose clamp than the band for a hose clamp is thick and that the tabs of each pair of tabs extend at a slant to the plane of the band from their base to the side of the leg onto which they are bent. In this configuration, a relatively large contact surface area between the edges of the holes and the tabs is provided in comparison to a configuration in which the edges of the holes and the tabs are crossing, one another at a right angle.
A further advantageous configuration resides in that each of the end portions of the legs of the loop provided with tabs is cut back to a reduced width in comparison to the main body of the band for a hose clamp up to the base of the tabs so that the band for a hose clamp has transverse edges and so that in a center plane of the band for a hose clamp perpendicular to the plane of the band, in the vicinity of the holes of each hole pair receiving a tab pair, a concave bead extends in the longitudinal direction of the band for a hose clamp. A backwardly bent end of the leg of the loop engages in a flush arrangement the hollow space of the bead. In this connection, a substantially continuous transition between the transverse edges of the end portion of the radially inwardly positioned leg of the loop having the tabs and the inner side of the remainder or main body of the band for a hose clamp is provided. When using a hose clamp provided with a band according to the invention for securing a hose on a pipe socket, the risk of a step-like transition of the inner diameter of the clamp hose occurring in the area of the transverse edges is substantially prevented so that a substantially uniform clamping force exerted by the clamp is realized about the circumference of the hose and, accordingly, a high sealing action of the connection between the hose and the pipe socket is ensured. At the same time, damage to the hose by such edges is prevented.
This configuration can be embodied in such a way that the bead extends between the holes of each pair of holes receiving a pair of tabs and that the material of the radially outer leg of the loop, when the band for a hose clamp is formed to the hose clamp, projects radially inwardly relative to the contour of the bead and the hose clamp in an area adjacent to the longitudinal sides of the bead, wherein the material of the outer leg of the loop projects at the transverse edges by the thickness of the band for a hose clamp and from these transverse edges, when viewed in the longitudinal direction of the bead, projects with a decreasing amount up to the contour of the bead.
An embodiment that is especially advantageous and long-lived comprises at least one of the projections embodied in the form of a rim hole which is riveted or upended at the side of the other leg.
As an alternative, the projections can be cup-shaped or nose-shaped and/or the projections can be the tabs.